In the layout design of a semiconductor device, there are various layout design methods according to the type of the semiconductor device. A layout design method examined by the inventors is a macro cell (mega cell) method, for example. This method is effective when a system, such as a micro processor, a memory, an I/O (input/output) device and a custom circuit, is constructed as a single chip, for example. The method is used to arrange various large and small circuit blocks in a chip area and performs wiring between the circuit blocks.